Women who took extra folic acid in the weeks before and just after becoming pregnant were less likely to have a child with autism, in a new study from Norway.
Because lack of folic acid has been tied to brain and spinal cord birth defects, groups including the U.S. Preventive Services Task Force (USPSTF) already call for women who may become pregnant to take daily supplements containing the B vitamin.
The new study "provides an additional reason to take folic acid, in addition to the preventive effect that we already know it has against neural tube defects," said Dr. Pal Suren from the Norwegian Institute of Public Health in Oslo, who led the research.
"It underlines the importance of starting early, preferably before the pregnancy," he told Reuters Health.
The new study, which appears in the Journal of the American Medical Association, doesn't prove low folic acid in pregnant women causes their babies to develop autism, or that high doses can prevent it. And Suren and his colleagues didn't see an effect of folic acid on other autism spectrum disorders, such as Asperger's.
They followed just over 85,000 women and their children, born between 2002 and 2008.
When women were about halfway through their pregnancies, they reported on any supplements or vitamins they'd taken in the few weeks before becoming pregnant and the two months afterward - the time when folic acid is thought to have the strongest effect on development.
By the time their kids were between three and 10 years old, 270 had been diagnosed with an autism spectrum disorder, including 114 with autism itself.
Suren's team found one in 1,000 babies born to women who reported taking folic acid early in pregnancy had autism, compared to about two in 1,000 of those whose moms didn't take folic acid. On the other hand, there was no link between fish oil taken during pregnancy and autism risk.
That suggests it's something about folic acid, in particular, that influences a baby's autism risk.
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